.. _examplere2rst:

================
Example with re2
================


.. only:: html

    **Links:** :download:`notebook <example_re2.ipynb>`, :downloadlink:`html <example_re22html.html>`, :download:`PDF <example_re2.pdf>`, :download:`python <example_re2.py>`, :downloadlink:`slides <example_re2.slides.html>`, :githublink:`GitHub|_doc/notebooks/example_re2.ipynb|*`


*wrapclib* wraps the library `re2 <https://github.com/google/re2>`__
using the wrapper `pyre2 <https://github.com/facebook/pyre2>`__.

.. code:: ipython3

    from jyquickhelper import add_notebook_menu
    add_notebook_menu()






.. contents::
    :local:





.. code:: ipython3

    from wrapclib import re2

Example with HTML
-----------------

.. code:: ipython3

    import re
    s = "<h1>mot</h1>"
    print(re.compile("(<.*>)").match(s).groups())


.. parsed-literal::
    ('<h1>mot</h1>',)


.. code:: ipython3

    s = "<h1>mot</h1>"
    print(re2.compile("(<.*>)").match(s).groups())


.. parsed-literal::
    ('<h1>mot</h1>',)


Group, Span
-----------

.. code:: ipython3

    s = """date 0 : 14/9/2000
    date 1 : 20/04/1971     date 2 : 14/09/1913     date 3 : 2/3/1978
    date 4 : 1/7/1986     date 5 : 7/3/47     date 6 : 15/10/1914
    date 7 : 08/03/1941     date 8 : 8/1/1980     date 9 : 30/6/1976"""
    
    expression = re2.compile(
        "([0-3]?[0-9]/[0-1]?[0-9]/([0-2][0-9])?[0-9][0-9])[^\d]")
    expression.search(s).group(1, 2)




.. parsed-literal::
    ('14/9/2000', '20')



.. code:: ipython3

    c = expression.search(s).span(1)
    s[c[0]:c[1]]




.. parsed-literal::
    '14/9/2000'



Names
-----

.. code:: ipython3

    date = "05/22/2010"
    exp = "(?P<jj>[0-9]{1,2})/(?P<mm>[0-9]{1,2})/(?P<aa>((19)|(20))[0-9]{2})"
    com = re2.compile(exp)
    print(com.search(date).groupdict())


.. parsed-literal::
    {'aa': '2010', 'jj': '05', 'mm': '22'}


findall
-------

*findall* is not natively implemented in *re2*. It was added.

.. code:: ipython3

    s = """date 0 : 14/9/2000
    date 1 : 20/04/1971     date 2 : 14/09/1913     date 3 : 2/3/1978
    date 4 : 1/7/1986     date 5 : 7/3/47     date 6 : 15/10/1914
    date 7 : 08/03/1941     date 8 : 8/1/1980     date 9 : 30/6/1976"""
    
    expression = re2.compile(
        "([0-3]?[0-9]/[0-1]?[0-9]/([0-2][0-9])?[0-9][0-9])[^\d]")
    
    re2.findall(expression, s)




.. parsed-literal::
    [('14/9/2000', '20'),
     ('20/04/1971', '19'),
     ('14/09/1913', '19'),
     ('2/3/1978', '19'),
     ('1/7/1986', '19'),
     ('7/3/47', None),
     ('15/10/1914', '19'),
     ('08/03/1941', '19'),
     ('8/1/1980', '19')]



benchmark
---------

.. code:: ipython3

    s = """date 0 : 14/9/2000
    date 1 : 20/04/1971     date 2 : 14/09/1913     date 3 : 2/3/1978
    date 4 : 1/7/1986     date 5 : 7/3/47     date 6 : 15/10/1914
    date 7 : 08/03/1941     date 8 : 8/1/1980     date 9 : 30/6/1976"""
    
    expression = re.compile(
        "([0-3]?[0-9]/[0-1]?[0-9]/([0-2][0-9])?[0-9][0-9])[^\d]")
    
    %timeit expression.findall(s)


.. parsed-literal::
    10.5 µs ± 296 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)


.. code:: ipython3

    %timeit re2.findall(expression, s)


.. parsed-literal::
    18.4 µs ± 1.51 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)


That’s expected as method *findall* is implemented in python and not C.